1. Field of the Invention:
The present invention relates to a lock system for an automatic door system a door member of which is moved so as to be opened and closed by means of an electric motor, and more particularly to an automatic-door lock system which makes it possible to lock a door member thereof to its closed positon without employing any detection switch for detecting a closed position of the door member.
2. Description of the Prior Art:
For example, as is clear from an automatic-door lock system disclosed in Japanese Patent Publication No. 62-54952, lock systems for locking the door members of automatic door systems to their closed positions at ends of closing strokes of the door members have been well known in the prior art for many years.
The converntional automatic-door lock system disclosed in the above Japanese Patent Publication comprises: a detection switch for detecting a closed position of a door member of an automatic door system; and a brake mechanism for stopping rotation of a pulley by energizing an electromagnet element for attracting the pulley to its stationary member. In operation, in the conventional automatic-door lock system, the detection switch detects the closed position of the door member at the end of the closing stroke of the door member so that the electromagnet element is energized through the detection switch so as to attract the pulley to its stationary member, whereby rotation of the pulley is stopped by friction caused between the pulley and the stationary member. As a result, it is possible for the conventional automatic-door lock system to lock the door member to its closed position.
In such conventional automatic-door lock system, the detection switch must be precisely positioned so as to be actuated at the end of the closing stroke of the door member. However, it is very difficult to precisely position the detection switch.